Abstract

Background & aims

Guidelines about recommendations for amounts of exercise/physical activity are variable in non alcoholic fatty liver disease (NAFLD). Our aim was to determine the amount of exercise that was associated with two outcomes: a) development of incident liver fat and b) resolution of baseline liver fat, at five year follow-up.

Methods

In an occupational health screening program, weekly frequency of exercise was assessed using the validated Korean version of the International Physical Activity Questionnaire Short Form (IPAQ-SF). Liver fat was identified by ultrasonography (3.5MHz probe) at baseline and at five year follow up. Fully adjusted Cox proportional hazards models were used to estimate hazard ratios (HRs and 95% confidence intervals) for incident fatty liver and resolution of fatty liver at follow up.

Results

233,676 men and women were studied between 2002 and 2014. 126,811 individuals were identified without fatty liver, and of these subjects, 29014 subjects developed incident fatty liver during follow up. At baseline, there were 42,536 individuals with liver fat and of these individuals, fatty liver resolved in 14,514, during follow up. After full adjustment, compared to no exercise, exercise was associated with benefit for both outcomes; for exercise ⩾5 times per week for incident fatty liver: HR 0.86 (95%CIs 0.80,0.92), p<0.001, and for resolution of fatty liver HR 1.40 (95%CIs 1.25,1.55), p<0.001.

Conclusions

Moderate to vigorous exercise is beneficial in decreasing risk of development of new fatty liver or improving resolution of existing fatty liver during 5 years of follow up.

The lay summary

The amount of exercise/physical activity to benefit fatty liver disease in non alcoholic fatty liver disease (NAFLD) is not known. In a large study of free-living people, our aim was to determine the amount of exercise that was linked with a decrease in new fatty liver and also improvement of existing fatty liver over 5 years of follow up. Compared to no exercise, exercise ⩾5 times per week (lasting at least 10 minutes on each occasion) was linked to a highly significantly benefit for both a decrease in new fatty liver and also improvement of existing fatty liver.